World population continues to grow at an astonishing rate and surveys suggest that both genders desire more male contraceptive options. Male hormonal contraceptive regimens that consist of androgens plus a progestin are attractive options as they have high efficacy rates (over 95%) and are fully reversible. However, little is known about the extra-gonadal effects of exogenous hormone administration in men. We propose two randomized, placebo-controlled trials that will further our understanding of the potential benefits and risks of androgens and progestins on the prostate and cardiovascular system, organ systems with high disease prevalence in men that might be modulated by androgens and progestins. We have recently developed technical expertise performing molecular analyses on prostate tissue specimens obtained from normal volunteers after hormone manipulation. We propose in Study 1 to determine intraprostatic hormone levels, cell turnover, and cell-specific gene expression in men treated with 3 months of testosterone (T) gel, T + dutasteride, a drug that blocks the conversion of T to the more potent androgen dihydrotestosterone and may contribute to prostate cancer prevention, or T + intramuscular depomedroxyprogesterone (IM DMPA), a promising male hormonal contraceptive regimen. This study will provide significant insights into the impact of hormonal manipulation on the prostate at the molecular level in normal, healthy men. Exogenous testosterone and progestins suppress serum high density lipoprotein (HDL) and cause weight gain. These changes may be associated with increased visceral adiposity, systemic inflammation, insulin resistance and increased risk of cardiovascular disease. Because there have been no systematic studies done on the effects of androgens + progestins on these cardiovascular risk factors, we propose in Study 2 to compare the effects of 6 months of treatment with T gel alone vs. T + IM DMPA vs. T + oral MPA on serum HDL, body composition, inflammatory markers, insulin sensitivity, and spermatogenesis. In Study 2, we will determine how T alone and T + IM DMPA affect these measures, and whether oral administration of the progestin MPA impacts these cardiovascular risk factors, and spermatogenesis, differently, due to first-pass hepatic effects. Together these studies will significantly advance our knowledge of the potential risks and benefits of T-based contraceptive regimens and T + MPA, a promising male hormonal contraceptive regimen.